U.S. patent number 10,001,318 [Application Number 14/400,372] was granted by the patent office on 2018-06-19 for heat pump device that draws heat from both the atmosphere and another heat source.
This patent grant is currently assigned to Mitsubishi Electric Corporation. The grantee listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Yoshiro Aoyagi, Yohei Kato.
United States Patent |
10,001,318 |
Kato , et al. |
June 19, 2018 |
Heat pump device that draws heat from both the atmosphere and
another heat source
Abstract
During heat applying operation, both an air-source heat
exchanger that exchanges heat with the atmosphere as a heat source
and an earth-source heat exchanger that uses geothermal heat as a
heat source serve as evaporators to collect heat from the
atmosphere and the geothermal heat. During defrosting operation,
while a four-way valve is switched to cause the air-source heat
exchanger to serve as a radiator, and the earth-source heat
exchanger to serve as an evaporator to collect the geothermal heat,
and the collected geothermal heat is collected in the main circuit
via the sub-circuit.
Inventors: |
Kato; Yohei (Tokyo,
JP), Aoyagi; Yoshiro (Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
N/A |
JP |
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|
Assignee: |
Mitsubishi Electric Corporation
(Tokyo, JP)
|
Family
ID: |
49583256 |
Appl.
No.: |
14/400,372 |
Filed: |
April 24, 2013 |
PCT
Filed: |
April 24, 2013 |
PCT No.: |
PCT/JP2013/062133 |
371(c)(1),(2),(4) Date: |
November 11, 2014 |
PCT
Pub. No.: |
WO2013/172166 |
PCT
Pub. Date: |
November 21, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150121913 A1 |
May 7, 2015 |
|
Foreign Application Priority Data
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|
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May 18, 2012 [WO] |
|
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PCT/JP2012/003271 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B
47/025 (20130101); F25D 21/06 (20130101); F25B
13/00 (20130101); F25D 21/004 (20130101); F25B
27/005 (20130101); F24D 3/18 (20130101); F25B
49/02 (20130101); Y02B 30/12 (20130101); F24D
2200/11 (20130101); F25B 2313/02531 (20130101); F25B
2313/02731 (20130101); F24D 2200/12 (20130101); F25B
2600/2507 (20130101); Y02B 10/40 (20130101); F25B
2313/02741 (20130101); F25B 2313/002 (20130101); F25B
2313/02533 (20130101); F24F 11/41 (20180101); F25B
2313/02542 (20130101) |
Current International
Class: |
F25B
41/00 (20060101); F25B 47/02 (20060101); F25D
21/06 (20060101); F24D 3/18 (20060101); F25B
27/00 (20060101); F25D 21/00 (20060101); F25B
13/00 (20060101); F25B 49/02 (20060101) |
Field of
Search: |
;62/81 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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53-016927 |
|
Jun 1978 |
|
JP |
|
58-85076 |
|
May 1983 |
|
JP |
|
61-272558 |
|
Dec 1986 |
|
JP |
|
03-117866 |
|
May 1991 |
|
JP |
|
08-086528 |
|
Apr 1996 |
|
JP |
|
2006-125769 |
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May 2006 |
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JP |
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2006-284022 |
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Oct 2006 |
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JP |
|
2006284022 |
|
Oct 2006 |
|
JP |
|
2009-243802 |
|
Oct 2009 |
|
JP |
|
2009-250495 |
|
Oct 2009 |
|
JP |
|
2009243802 |
|
Oct 2009 |
|
JP |
|
2011-179692 |
|
Sep 2011 |
|
JP |
|
2010/143373 |
|
Dec 2010 |
|
WO |
|
Other References
Aoyama, Yutaka, JP 2009-243802, English Translation, European
Patent Office. cited by examiner .
Partial supplementary European search report dated May 30, 2016 in
the corresponding EP application No. 13791128.5. cited by applicant
.
International Search Report of the International Searching
Authority dated Jul. 30, 2013 for the corresponding international
application No. PCT/JP2013/062133 (and English translation). cited
by applicant .
Office Action dated Jul. 7, 2015 in corresponding JP patent
application No. 2014-515556 (and English translation). cited by
applicant .
Office Action dated Sep. 29, 2015 in the corresponding JP
application No. 2014-515556 (with English translation). cited by
applicant .
Extended European Search Report dated Nov. 2, 2016 issued in
corresponding EP patent application No. 13791128.5. cited by
applicant.
|
Primary Examiner: Jules; Frantz
Assistant Examiner: Tanenbaum; Steve
Attorney, Agent or Firm: Posz Law Group, PLC
Claims
The invention claimed is:
1. A heat pump device comprising: a refrigerant circuit which
includes a main circuit in which a compressor, a refrigerant flow
path of a load side heat exchanger, a first pressure reducing
device, and a first heat source heat exchanger, which is configured
to exchange heat with a first heat source, are connected in order,
wherein the first heat source is the atmosphere, a refrigerant
circulates through the main circuit, the main circuit has a first
pipe that connects the first pressure reducing device to the load
side heat exchanger, the main circuit has a second pipe that
connects the first pressure reducing device to the first heat
source heat exchanger, and the second pipe is separate from the
first pipe, a sub-circuit in which a second pressure reducing
device and a refrigerant flow path of a second heat source heat
exchanger are connected in series, wherein the sub-circuit has a
first end and a second end, and the first end is connected with a
branch pipe branching from the first pipe, a first switching device
connected to the second end of the sub-circuit and configured to
switch a connection of the refrigerant flow path of the second heat
source heat exchanger; a heat exchange medium circuit, which
includes a heat exchange medium flow path of the second heat source
heat exchanger, wherein a heat exchange medium that exchanges heat
with a second heat source, which is different from the atmosphere,
circulates through the heat exchange medium circuit to take away
heat of the second heat source; and a controller configured to
control the first switching device, wherein during a defrosting
operation, wherein the controller causes the first heat source heat
exchanger to serve as a radiator and the second heat source heat
exchanger to serve as an evaporator, switches the first switching
device to connect the refrigerant flow path of the second heat
source heat exchanger with a suction side of the compressor, and
allows the second heat source heat exchanger to exchange heat
between the main circuit and the sub-circuit to use the second heat
source upon for defrosting the first heat source heat
exchanger.
2. The heat pump device of claim 1, further comprising a second
switching device provided on a discharge side of the compressor,
wherein during the defrosting operation, the controller switches
the second switching device to cause the first heat source heat
exchanger to serve as a radiator and the second heat source heat
exchanger to serve as an evaporator.
3. The heat pump device of claim 1, further comprising: a second
switching device provided on a discharge side of the compressor; a
defrosting circuit which is formed by blocking a part of a flow
path of the refrigerant circuit and in which the refrigerant
circulates between the first heat source heat exchanger and the
second heat source heat exchanger; and a refrigerant pump which is
provided on the defrosting circuit and configured to circulate the
refrigerant, wherein during the defrosting operation, the
controller performs defrosting using either one of: a method in
which the second switching device is switched such that the first
heat source heat exchanger serves as a radiator and the second heat
source heat exchanger serves as an evaporator, and the first
switching device is switched to the suction side of the compressor
to perform defrosting; and a method in which the compressor is
stopped, the defrosting circuit is formed, and the refrigerant pump
is operated to circulate, through the defrosting circuit, the
refrigerant having collected the heat of the second heat source
from the heat exchange medium circuit via the second heat source
heat exchanger, thereby performing defrosting.
4. The heat pump device of claim 1, further comprising: a second
switching device provided on a discharge side of the compressor;
and a defrosting circuit which is formed by blocking a part of a
flow path of the refrigerant circuit and in which the refrigerant
circulates between the first heat source heat exchanger and the
second heat source heat exchanger, wherein the first heat source
heat exchanger is disposed at a position higher than the second
heat source heat exchanger and configured such that the refrigerant
having collected the heat of the second heat source from the heat
exchange medium circuit via the second heat source heat exchanger
undergoes natural circulation through the defrosting circuit, and
during the defrosting operation, the controller performs defrosting
using either one of: a method in which the second switching device
is switched such that the first heat source heat exchanger serves
as a radiator and the second heat source heat exchanger serves as
an evaporator, and the first switching device is switched to the
suction side of the compressor to perform defrosting; and a method
in which the compressor is stopped, the defrosting circuit is
formed, and defrosting is performed by natural circulation.
5. The heat pump device of claim 1, wherein the main circuit is
configured such that a connection destination, on a side opposite
to the first pressure reducing device, of the first heat source
heat exchanger is switched by the first switching device, the
sub-circuit is configured such that an end, opposite to the second
pressure reducing device, of the refrigerant flow path of the
second heat source heat exchanger is connected to the end of the
compressor on the suction side thereof, the refrigerant circuit is
configured to perform at least heat applying operation in which the
refrigerant circulates such that the load side heat exchanger
serves as a radiator and the first heat source heat exchanger
serves as an evaporator, by switching the first switching device
such that the connection destination, on the side opposite to the
first pressure reducing device, of the first heat source heat
exchanger is on a junction and branch point side with respect to
the second heat source heat exchanger, and during the defrosting
operation, the controller switches the first switching device so
that the connection destination, on the side opposite to the first
pressure reducing device, of the first heat source heat exchanger
is on a discharge side of the compressor, and allows a part of the
refrigerant discharged from the compressor to flow into the first
heat source heat exchanger.
6. The heat pump device of claim 1, further comprising an auxiliary
compressor provided between the junction and branch point of the
refrigerant circuit and the first heat source heat exchanger via
the first switching device, wherein the main circuit is configured
such that a connection destination, on a side opposite to the first
pressure reducing device, of the first heat source heat exchanger
is switched by the first switching device, the sub-circuit is
configured such that an end, opposite to the second pressure
reducing device, of the refrigerant flow path of the second heat
source heat exchanger is connected to the end of the compressor on
the suction side thereof, the refrigerant circuit is configured to
perform at least heat applying operation in which the refrigerant
circulates such that the load side heat exchanger serves as a
radiator and the first heat source heat exchanger serves as an
evaporator, by switching the first switching device such that the
connection destination, on the side opposite to the first pressure
reducing device, of the first heat source heat exchanger is on a
junction and branch point side with respect to the second heat
source heat exchanger, and during the defrosting operation, the
controller switches the first switching device so that the
connection destination, on the side opposite to the first pressure
reducing device, of the first heat source heat exchanger is on a
discharge side of the auxiliary compressor, and causes a part of
the refrigerant having flowed out of the refrigerant flow path of
the second heat source heat exchanger to be compressed by the
auxiliary compressor and flow into the first heat source heat
exchanger.
7. The heat pump device of claim 1, wherein a heat source having a
temperature lower than a temperature set for a load side device in
which the load side heat exchanger is installed is used as the
second heat source.
8. The heat pump device of claim 7, wherein any one of geothermal
heat, groundwater, seawater, and solar hot water is used as the
second heat source.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a U.S. national stage application of
PCT/JP2013/062133 filed on Apr. 24, 2013, which claims priority to
international application no. PCT/JP2012/003271, filed on May 18,
2012, the contents of which are incorporated herein by
reference.
TECHNICAL FIELD
The present invention relates to a heat pump device.
BACKGROUND
A heat pump device used in a heating and cooling apparatus or a
water heater generally uses air as a heat source.
In addition, in a region where the atmospheric temperature is low,
a heat pump that uses geothermal heat during heating has also been
used recently.
In an air-source heat pump device which uses the heat of the
atmosphere as a heat source, when the atmospheric temperature is
low during heating operation, the heating capacity may be decreased
due to a decrease in suction pressure, frost, or the like. As
described above, the operating efficiency of the heat pump device
depends on the atmospheric temperature.
In a geothermal heat pump device which uses geothermal heat, when
the underground temperature is higher than the atmospheric
temperature, the operating efficiency is higher than that of the
air-source heat pump since it is possible to increase an amount of
collected heat. However, when the underground temperature is lower
than the atmospheric temperature, the operating efficiency is lower
than that of the air-source heat pump device.
In addition, the underground temperature is generally less varied
throughout the year than the atmospheric temperature, but its
variation range depends on a region, a depth, and a season, and
thus the operating efficiency is lower than that of the air-source
heat pump in some cases.
As a solution to these problems, Patent Literature 1 discloses a
technique to switch between an air heat exchanger installed on the
ground and an underground heat exchanger buried underground in
accordance with a result of comparison between the atmospheric
temperature and the underground temperature.
PATENT LITERATURE
Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2006-125769 (FIG. 1, FIG. 3)
As disclosed in Patent Literature 1, in the case where the
underground heat exchanger and the air heat exchanger are
selectively used depending on the underground temperature and the
atmospheric temperature, the underground heat exchanger and the air
heat exchanger are designed for their sizes such that the
processing capacities thereof are the same. In general, an
underground heat exchanger needs to have a larger size than that of
an air heat exchanger in order to obtain the same processing
capacity, and also needs to be buried underground and requires
construction cost for a digging operation and the like. Thus, in a
configuration in which an underground heat exchanger having the
same processing capacity as that of an air heat exchanger is
provided, a significant increase in cost is caused as compared to a
heat pump device using solely an air heat source or an underground
heat source.
Thus, when an underground heat exchanger and an air heat exchanger
are not selectively used to collect heat from either one but heat
is collected simultaneously from the atmosphere and the
underground, the air heat exchanger compensates for a part of an
amount of heat collected by the underground heat exchanger.
Therefore, it is possible to reduce the necessary size of the
underground heat exchanger, and there is the advantageous that it
is possible to reduce the system cost.
However, in the configuration in which heat is collected
simultaneously from the atmosphere and the underground, for
example, when the load of a room is low and the power input to a
compressor is low, the power of a geothermal heat pump provided in
an earth-source side circuit including the underground heat
exchanger accounts for an increased proportion of the entire
system. In this case, even when the temperature of the atmosphere
is low (e.g., around 0 degrees C.), the system efficiency may be
higher when heat is collected using the air heat exchanger than
when heat is collected using the underground heat exchanger. In
this case, heat is collected using the air heat exchanger, the air
heat exchanger serves as an evaporator in the low-temperature
atmosphere, and thus frost occurs on the air heat exchanger.
Therefore, it is necessary to perform defrosting operation in order
to prevent a decrease in heat exchange performance of the air heat
exchanger due to frost.
As a general defrosting method of a heat pump device using an air
heat exchanger, a method in which an amount of work of a compressor
is used as a heat source and a refrigerant discharged from the
compressor is supplied directly to an air heat exchanger (to be
referred to as a hot gas method hereinafter) or a method in which a
refrigerant flow path is switched for cooling operation and heat on
a load side (indoor side) is collected and used as a heat source
for defrosting (to be referred to as a reverse method hereinafter),
is used.
In the hot gas method, since no heat is rejected to the load side,
the comfort is maintained. However, since an amount of heat used
for defrosting is only the amount of work of the compressor, there
is the drawback that the defrosting period of time is lengthened
and the power consumption increases. In addition, in the reverse
method, since the heat on the load side is collected, an amount of
heat used for defrosting is large, and the defrosting period of
time is short, but there is the drawback that the comfort is
deteriorated.
Meanwhile, in the recent years, other than the atmosphere,
geothermal heat has been increasingly used as a heat source in a
heat pump device as described above, but use of other heat sources
other than geothermal heat has also been desired.
SUMMARY
The present invention has been made in view of such points, and an
object of the present invention is to provide a heat pump device
that has a configuration of collecting heat from both the
atmosphere and another heat source and is able to suppress
deterioration of the comfort and the power consumption during
defrosting operation.
A heat pump device according to the present invention includes: a
refrigerant circuit which includes a main circuit in which a
compressor, a refrigerant flow path of a load side heat exchanger,
a first pressure reducing device, and a first heat source heat
exchanger configured to exchange heat with atmosphere are connected
in order, and through which a refrigerant circulates, and a
sub-circuit in which a second pressure reducing device and a
refrigerant flow path of a second heat source heat exchanger are
connected in series with a branch pipe branching from a pipe
defined between the first pressure reducing device and the load
side heat exchanger of the main circuit and which is switched by a
first switching device such that a connection destination, on a
side opposite to the second pressure reducing device, of the
refrigerant flow path of the second heat source heat exchanger is
on a junction and branch point side with respect to the first heat
source heat exchanger or an end of the compressor on a suction side
thereof; a heat exchange medium circuit which includes a heat
exchange medium flow path of the second heat source heat exchanger,
and through which a heat exchange medium exchanging heat with
another heat source different from the atmosphere to take away heat
of the other heat source circulates; and a controller configured to
control the first switching device. During defrosting operation,
the controller causes the first heat source heat exchanger to serve
as a radiator and the second heat source heat exchanger to serve as
an evaporator, switches the first switching device to the suction
side of the compressor, and allows the heat collected from the
other heat source by the heat exchange medium circuit to be
collected in the main circuit via the sub-circuit upon heat
exchange in the second heat source heat exchanger and be used as a
heat source for defrosting of the second heat source heat
exchanger.
According to the present invention, it is possible to use a heat
source other than the atmosphere as a heat source for defrosting,
and it is possible to suppress power consumption during defrosting
operation without deterioration of the comfort.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram showing a refrigerant circuit of an
air-conditioning apparatus to which a heat pump device according to
Embodiment 1 of the present invention is applied.
FIG. 2 is a diagram showing flow of a refrigerant during heating
operation in Embodiment 1.
FIG. 3 is a p-h diagram during heating operation in FIG. 2.
FIG. 4 is a diagram showing flow of the refrigerant during cooling
operation in Embodiment 1.
FIG. 5 is a p-h diagram during cooling operation in FIG. 4.
FIG. 6 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 1.
FIG. 7 is a p-h diagram during defrosting operation in FIG. 6.
FIG. 8 is a flowchart showing flow of a process during defrosting
operation in the air-conditioning apparatus of Embodiment 1 of the
present invention.
FIG. 9 is a diagram (part 1) showing a modification of Embodiment 1
of the present invention.
FIG. 10 a diagram (part 2) showing a modification of Embodiment 1
of the present invention.
FIG. 11 is a diagram showing a refrigerant circuit of an
air-conditioning system including a heat pump device of Embodiment
2 of the present invention.
FIG. 12 is a diagram showing flow of a refrigerant during heating
operation in Embodiment 2.
FIG. 13 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 2.
FIG. 14 is a p-h diagram during defrosting operation in FIG.
13.
FIG. 15 is a diagram showing a modification of the refrigerant
circuit of the air-conditioning system including the heat pump
device of Embodiment 2 of the present invention.
FIG. 16 is a diagram showing a refrigerant circuit of an
air-conditioning system including a heat pump device of Embodiment
3 of the present invention.
FIG. 17 is a diagram showing flow of a refrigerant during heating
operation in Embodiment 3.
FIG. 18 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 3.
FIG. 19 is a p-h diagram during defrosting operation in FIG.
18.
FIG. 20 is a diagram showing a refrigerant circuit of an
air-conditioning system including a heat pump device of Embodiment
4 of the present invention.
FIG. 21 is a diagram showing flow of a refrigerant during heating
operation in Embodiment 4.
FIG. 22 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 4.
FIG. 23 is a p-h diagram during defrosting operation in FIG.
22.
DETAILED DESCRIPTION
Embodiments will be described below assuming a load side apparatus
to which a heat pump device is applied as an air-conditioning
apparatus that performs cooling or heating.
Embodiment 1
FIG. 1 is a diagram showing a refrigerant circuit of an
air-conditioning apparatus to which a heat pump device of
Embodiment 1 of the present invention is applied.
An air-conditioning apparatus 100 includes a heat pump device 40
and a load side circuit 51 through which a load side medium
circulates, and also includes a load side device 50 that performs
cooling or heating with the heat pump device 40 as a heat
source.
<<Heat Pump Device>>
The heat pump device 40 includes a refrigerant circuit 10 through
which a refrigerant circulates, an earth-source side circuit 20,
and a controller 30, and is installed outdoors.
<Refrigerant Circuit>
The refrigerant circuit 10 includes a main circuit 10a in which a
compressor 1, a four-way valve 2 serving as a second switching
device, a water heat exchanger 3 serving as a load side heat
exchanger, an expansion valve 4a serving as a first pressure
reducing device, and an air-source heat exchanger 5a serving as a
first heat source heat exchanger are connected in order, and
through which the refrigerant circulates, and a sub-circuit 10b. In
the sub-circuit 10b, an expansion valve 4b and a refrigerant flow
path 41 of an earth-source heat exchanger 5b are connected in
series with a branch pipe 11a branching from a pipe defined between
the expansion valve 4a and the water heat exchanger 3 of the main
circuit 10a, and the refrigerant flow path 41 of the earth-source
heat exchanger 5b is connected, on its side opposite to the
expansion valve 4b, to the air-source heat exchanger 5a (the end of
the air-source heat exchanger 5a on its side opposite to the
expansion valve 4a) or the end of the compressor 1 on its suction
side via a three-way valve 6 serving as a first switching device.
In the main circuit 10a, a refrigerant container 7a is provided
which serves as a buffer container for preventing rapid liquid
return to the compressor 1. The refrigerant container 7a also
serves as a container that stores an excess refrigerant.
(Compressor)
The compressor 1 is implemented in, for example, a completely
hermetically sealed compressor, and has a configuration in which an
electric motor portion (not shown) and a compressing portion (not
shown) are housed in a compressor shell (not shown). A low-pressure
refrigerant drawn into the compressor 1 by suction is compressed
into a high-temperature and high-pressure refrigerant and
discharged from the compressor 1. The rotation speed of the
compressor 1 is controlled via an inverter (not shown) by the
controller 30, thereby controlling the capacity of the heat pump
device 40.
(Water Heat Exchanger)
The water heat exchanger 3 exchanges heat between the load side
medium (in this case, water) in a water circuit 51 for cooling and
heating which serves as a load side circuit 51 of the load side
device 50 and the refrigerant in the refrigerant circuit 10. The
water circulates through the water circuit 51 by a pump 52. In
heating, the water heat exchanger 3 serves as a condenser and heats
the water with the heat of the refrigerant in the refrigerant
circuit 10 to generate hot water. In cooling, the water heat
exchanger 3 serves as an evaporator and cools the water with the
cooling energy of the refrigerant in the refrigerant circuit 10 to
generate cold water. A room is heated or cooled by using the hot
water or cold water. Examples of the form of the heat exchanger
include a plate heat exchanger in which plates are stacked, and a
double pipe heat exchanger including a heat-transfer pipe through
which a refrigerant flows and a heat-transfer pipe through which
water flows. Either form may be used in Embodiment 1. The load side
medium that circulates through the load side circuit 51 is not
limited to water, and may be an antifreeze solution such as
brine.
(Expansion Valve)
The expansion valve 4a adjusts the flow rate of the refrigerant
flowing through the air-source heat exchanger 5a. In addition, the
expansion valve 4b serving as a second pressure reducing device
adjusts the flow rate of the refrigerant flowing through an
underground heat exchanger 21. The opening degrees of the expansion
valves 4a and 4b are variably set on the basis of a control signal
from the controller 30. Each expansion valve can not only be an
electronic expansion valve whose opening degree can be changed in
accordance with an electrical signal, but also be an expansion
valve in which a plurality of orifices or capillaries are connected
in parallel and the flow rate of the refrigerant flowing into the
heat exchanger is controllable through an operation of
opening/closing a valve such as a solenoid valve.
(Air-Source Heat Exchanger)
The air-source heat exchanger 5a is implemented in, for example, a
fin-and-tube heat exchanger formed from copper or aluminum. The
air-source heat exchanger 5a exchanges heat between the refrigerant
and the outdoor air supplied from a fan 8 serving as a heat medium
transfer device.
(Three-Way Valve)
The three-way valve 6, which serves as a first switching device, is
used to switch the flow pattern of the refrigerant in the
earth-source heat exchanger 5b between the duration of normal
operation (heating operation or cooling operation) and the duration
of the defrosting operation of the air-source heat exchanger 5a.
Specifically, during normal operation, the flow pattern of the
refrigerant that leaves the earth-source heat exchanger 5b is
switched to the one which enables entrance to the air-source heat
exchanger 5a such that both the air-source heat exchanger 5a and
the earth-source heat exchanger 5b serve as condensers (radiators)
or evaporators. On the other hand, during defrosting operation, the
flow pattern of the refrigerant that leaves the earth-source heat
exchanger 5b is switched to the one which enables entrance to the
end of the compressor 1 on its suction side such that the
air-source heat exchanger 5a serves as a condenser and the
earth-source heat exchanger 5b serves as an evaporator.
(Four-Way Valve)
The four-way valve 2, which serves as a second switching device, is
used to switch the flow pattern of the refrigerant in the
refrigerant circuit 10. By switching the flow path, the water heat
exchanger 3 can be used as a condenser during heating operation and
as an evaporator during cooling operation.
<<Earth-Source Side Circuit>>
The earth-source side circuit 20 serving as a heat exchange medium
circuit is configured such that an earth-source side medium flow
path 42 of the earth-source heat exchanger 5b serving as a second
heat source heat exchanger, the underground heat exchanger 21 that
is buried underground, and a geothermal heat pump 22 are connected
in order, and an earth-source side medium serving as a heat
exchange medium implemented using an antifreeze solution such as
brine circulates through them, thereby collecting geothermal
heat.
(Underground Heat Exchanger)
The underground heat exchanger 21 includes, for example, a group of
heat collecting pipes that are formed in an almost U shape, is
buried vertically or horizontally underground, and is made of a
resin. The underground heat exchanger 21 has a heat exchange
capacity that varies depending on where or how deep the group of
heat collecting pipes is buried. In the underground heat exchanger
21, the earth-source side medium passing through it collects heat
from the underground.
(Earth-Source Heat Exchanger)
The earth-source heat exchanger 5b exchanges heat between the
refrigerant circulating through the refrigerant circuit 10 and the
earth-source side medium circulating through the earth-source side
circuit 20. In the earth-source heat exchanger 5b, the earth-source
side medium having collected geothermal heat by the underground
heat exchanger 21 flows into the earth-source side medium flow path
42, and thus the heat collected from the underground by the
underground heat exchanger 21 is transmitted to the refrigerant in
the refrigerant flow path 41. Accordingly, the refrigerant circuit
10 collects the geothermal heat. Similarly to the water heat
exchanger 3, examples of the form of the earth-source heat
exchanger 5b include a plate heat exchanger and a double pipe heat
exchanger, and either form may be used.
<Explanation of Sensor>
The heat pump device 40 is provided with a temperature or pressure
sensor where necessary. A value detected by each sensor is input to
the controller 30 and used to control the operation of the heat
pump device 40, for example, to control the capacity of the
compressor 1 and controlling the opening degrees of the expansion
valves 4a and 4b. Referring to FIG. 1, a refrigerant temperature
sensor 31, an atmospheric temperature sensor 32, and a geothermal
temperature sensor 33 are provided.
The refrigerant temperature sensor 31 detects the saturation
temperature of a low-pressure refrigerant in the refrigerant
circuit 10. The atmospheric temperature sensor 32 detects the
temperature of the atmosphere which serves as a heat source side
heat medium. The geothermal temperature sensor 33 detects the
temperature (geothermal temperature) of the earth-source side
medium pumped up from the underground heat exchanger 21 by the
geothermal heat pump 22. As shown in FIG. 1, the refrigerant
temperature sensor 31 may be a suction pressure sensor 34 that
detects the pressure of the refrigerant on the suction side of the
compressor 1. In this case, the refrigerant pressure obtained by
the suction pressure sensor 34 may be converted into a refrigerant
saturation temperature by the controller 30.
Next, each operation in the air-conditioning apparatus will be
described with reference to FIGS. 2, 4, and 6 showing flow of the
refrigerant and FIGS. 3, 5, and 7 which are p-h diagrams (diagrams
showing the relationship between the pressure and the specific
enthalpy of the refrigerant). Referring to FIGS. 2 and 4, an
alternate long and short dashed line indicates a pipe portion
through which the refrigerant does not flow. In addition, referring
to FIGS. 2, 4, and 6, [i] (i=1, 2, . . . ) indicates a refrigerant
state at each pipe position shown in FIGS. 3, 5, and 7.
Each operation in the air-conditioning apparatus will be described
hereinafter. The heat pump device of the present invention is a
device that simultaneously collects heat from both the atmosphere
and the underground. In any of the operations to be described
below, the geothermal heat pump 22 of the earth-source side circuit
20 operates, and geothermal heat is collected.
(Refrigerant Operation During Normal Operation (Heating
Operation))
The operation of the air-conditioning apparatus in normal
operation, particularly, in heating operation, according to
Embodiment 1 will be described. During heating operation, each of
the four-way valve 2 and the three-way valve 6 is switched to a
side indicated by a dotted line in FIG. 1.
FIG. 2 is a diagram showing flow of the refrigerant during heating
operation in Embodiment 1. FIG. 3 is a diagram showing the
relationship between the operation state and the temperature of the
heat source side heat medium (the atmospheric temperature and the
geothermal temperature) during heating operation in FIG. 2. Note
that the geothermal temperature is higher than the air
temperature.
The low-temperature and low-pressure refrigerant (state [1]) is
compressed by the compressor 1 into a high-temperature and
high-pressure refrigerant (state [2]) and discharged from it. The
high-temperature and high-pressure refrigerant discharged from the
compressor 1 passes through the four-way valve 2 switched for
heating, flows into the water heat exchanger 3, and rejects heat to
the water in the water circuit 51. The refrigerant (state [3])
obtained as a low-temperature and high-pressure refrigerant due to
the heat rejection to the water divides into two streams, which
individually flow into the expansion valves 4a and 4b.
The refrigerant having flowed into the expansion valve 4a is
reduced in pressure into a refrigerant in state [4], and flows into
the air-source heat exchanger 5a. The refrigerant having flowed
into the air-source heat exchanger 5a evaporates upon taking away
heat from the outdoor air, and then flows out of the air-source
heat exchanger 5a. On the other hand, the refrigerant having flowed
into the expansion valve 4b is reduced in pressure into a
refrigerant in state [4'], and flows into the earth-source heat
exchanger 5b. The refrigerant having flowed into the earth-source
heat exchanger 5b exchanges heat with the earth-source side medium
to take away heat from it. Upon this heat exchange operation,
geothermal heat is collected. Then, the refrigerant having
evaporated upon the collection of the geothermal heat joins, at a
junction and branch point P, the refrigerant having flowed out of
the air-source heat exchanger 5a of the main circuit 10a, passes
through the four-way valve 2 and the refrigerant container 7a, and
is drawn into the compressor 1 by suction again.
(Refrigerant Operation During Normal Operation (Cooling
Operation))
Next, the operation of the air-conditioning apparatus in normal
operation, particularly, in cooling operation, according to
Embodiment 1 will be described. During cooling operation, the
four-way valve 2 is switched to a side indicated by a solid line in
FIG. 1, and the three-way valve 6 is switched to the side indicated
by the dotted line in FIG. 1.
FIG. 4 is a diagram showing flow of the refrigerant during cooling
operation in Embodiment 1. FIG. 5 is a diagram showing the
relationship between the operation state and the temperature of the
heat source side heat medium (the atmospheric temperature and the
underground temperature) during cooling operation in FIG. 4. Note
that the geothermal temperature is lower than the air
temperature.
The low-temperature and low-pressure refrigerant (state [1]) is
compressed by the compressor 1 into a high-temperature and
high-pressure refrigerant (state [2]) and discharged from it. The
high-temperature and high-pressure refrigerant discharged from the
compressor 1 passes through the four-way valve 2 switched for
cooling and then divides into two streams at the junction and
branch point P, one of the two streams flows into the air-source
heat exchanger 5a, and the other stream flows into the earth-source
heat exchanger 5b via the three-way valve 6.
The refrigerant having flowed into the air-source heat exchanger 5a
rejects heat to the atmosphere to become a low-temperature and
high-pressure refrigerant (state [3]), flows out of the air-source
heat exchanger 5a, and flows into and is decompressed by the
expansion valve 4a. On the other hand, the refrigerant having
flowed into the earth-source heat exchanger 5b rejects heat to the
earth-source side medium to become a low-pressure high-pressure
refrigerant (state [3']), flows out of the earth-source heat
exchanger 5b, and flows into and is decompressed by the expansion
valve 4b. Then, the refrigerant reduced in pressure by the
expansion valve 4b joins the refrigerant reduced in pressure by the
expansion valve 4a, to become a refrigerant in state [4], and flows
into the water heat exchanger 3. The refrigerant having flowed into
the water heat exchanger 3 evaporates upon taking away heat from
the water in the water circuit 51, passes through the four-way
valve 2 and the refrigerant container 7a, and is drawn into the
compressor 1 by suction again.
(Refrigerant Operation During Defrosting Operation)
Next, the operation of the air-conditioning apparatus in defrosting
operation in Embodiment 1 will be described. During defrosting
operation, each of the four-way valve 2 and the three-way valve 6
is switched to the side indicated by the solid line in FIG. 1.
FIG. 6 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 1. FIG. 7 is a diagram showing
the operation state and the temperature of the heat source side
heat medium (the atmospheric temperature and the underground
temperature) during defrosting operation in FIG. 6. Note that the
geothermal temperature is higher than the air temperature.
The low-temperature and low-pressure refrigerant (state [1]) is
compressed by the compressor 1 into a high-temperature and
high-pressure refrigerant (state [2]) and discharged from it. The
high-temperature and high-pressure refrigerant discharged from the
compressor 1 passes through the four-way valve 2 switched for
defrosting (in the same manner as in cooling) and flows into the
air-source heat exchanger 5a. Then, the refrigerant having flowed
into the air-source heat exchanger 5a condenses into a
low-temperature and high-pressure refrigerant upon rejecting heat
to frost adhering on the air-source heat exchanger 5a or the
atmosphere, which serves as a heat source side heat medium (state
[3]). The thus obtained low-temperature and high-pressure
refrigerant flows into the expansion valve 4a and is reduced in
pressure into a refrigerant in state [4].
The refrigerant in state [4] divides into two streams, and one of
the two streams flows into the water heat exchanger 3, evaporates
upon taking away heat from the water in the water circuit 51, and
flows out of the water heat exchanger 3. The other stream flows
into the expansion valve 4b of the sub-circuit 10b, is further
reduced in pressure into a low-temperature and low-pressure
refrigerant (state [4']), flows into the earth-source heat
exchanger 5b, and exchanges heat with the earth-source side medium
to take away heat from it. Upon this heat exchange operation,
geothermal heat is collected. Then, the refrigerant in the
sub-circuit 10b having evaporated upon the collection of the
geothermal heat passes through the three-way valve 6 and flows
toward the four-way valve 2. The refrigerant flowing toward the
four-way valve 2 joins the refrigerant, on the side of the main
circuit 10a, having flowed out of the water heat exchanger 3 and
having passed through the four-way valve 2, passes through the
refrigerant container 7a, and is drawn into the compressor 1 by
suction again.
In this defrosting operation, almost the same cycle as in normal
cooling operation is obtained in the main circuit 10a, and a
high-temperature refrigerant discharged from the compressor 1 flows
into the air-source heat exchanger 5a. Thus, it is possible to melt
the frost adhering on the air-source heat exchanger 5a. On the
other hand, in the earth-source side circuit 20, the earth-source
side medium in the underground heat exchanger 21 exchanges heat
with the underground to collect geothermal heat, and the
earth-source side medium having collected the geothermal heat
exchanges heat with the refrigerant in the sub-circuit 10b, through
the underground heat exchanger 21. Thus, the geothermal heat is
collected by the refrigerant in the sub-circuit 10b, and the
refrigerant stream in the sub-circuit 10b having collected the
geothermal heat merges with the refrigerant stream flowing into the
main circuit 10a, and the heat is collected into the main circuit
10a. Thus, during defrosting, not only the amount of work of the
compressor 1, but also the amount of heat collected from the
earth-source heat exchanger 5b can be used as an amount of heat for
defrosting.
(Defrosting Operation Control Method)
FIG. 8 is a flowchart showing flow of a process during defrosting
operation in the air-conditioning apparatus of Embodiment 1 of the
present invention.
During heating operation (S1), the controller 30 of the
air-conditioning apparatus determines whether defrosting operation
is required, on the basis of a value detected by the sensor or the
like (S2). For example, the following methods are available as
common examples of determination as to whether defrosting is
required. In one method, it is determined that defrosting is
required, when the difference between a temperature detected by the
refrigerant temperature sensor 31 or a temperature corresponding to
the value detected by the suction pressure sensor 34 and an
atmospheric temperature detected by the atmospheric temperature
sensor 32 becomes a predetermined value. In another method, it is
determined that defrosting is required, when the atmospheric
temperature is equal to or lower than a predetermined value and the
heating operation has been done for a period of time equal to or
greater than a predetermined value.
It is determined whether defrosting is required, by such a
determination method. If it is determined that defrosting is
required, the four-way valve 2 and the three-way valve 6 are
switched in a way as shown in FIG. 6, and defrosting operation is
started. Specifically, the flow path of the four-way valve 2 is
switched in the same way as in cooling operation such that the
air-source heat exchanger 5a serves as a condenser (S3). In
addition, the three-way valve 6 is switched to the suction side of
the compressor 1 (S4) to form a flow path through which the
earth-source heat exchanger 5b and the end of the compressor 1 on
the suction side communicate with each other. Thus, the
earth-source heat exchanger 5b serves as an evaporator.
By switching the four-way valve 2 and the three-way valve 6 in the
above-described way, defrosting of the air-source heat exchanger 5a
is started, as described above, and the frost adhering on the
air-source heat exchanger 5a is melted by the high-temperature and
high-pressure refrigerant flowing into the air-source heat
exchanger 5a. After the start of defrosting operation, if the
controller 30 determines that the frost has been removed (S5), the
controller 30 ends defrosting operation. Presence/absence of the
frost may be determined on the basis of, for example, whether the
condensing temperature is equal to or higher than a predetermined
value, or whether a set defrosting operation period of time has
elapsed. If the controller 30 determines that the defrosting is to
end, the controller 30 switches the flow paths of the three-way
valve 6 and the four-way valve 2 and performs heating operation
again (S6).
As described above, according to Embodiment 1, during heating
operation, both the air-source heat exchanger 5a which exchanges
heat with the atmosphere serving as a heat source, and the
earth-source heat exchanger 5b which uses geothermal heat as a heat
source, serve as evaporators to collect heat from both the
atmosphere and another heat source. During defrosting operation,
the four-way valve 2 is switched, and the air-source heat exchanger
5a serves as a radiator, while the earth-source heat exchanger 5b
serves as an evaporator, and heat collected from the underground by
the earth-source side circuit 20 is collected into the main circuit
10a via the sub-circuit 10b. Thus, it is possible to use the
geothermal heat as a heat source for defrosting. Therefore, the
amount of heat available during defrosting operation increases, and
it is possible to reduce the defrosting period of time.
In addition, since a part of the refrigerant having flowed out of
the air-source heat exchanger 5a during defrosting operation flows
into the earth-source heat exchanger 5b, the flow rate of the
refrigerant flowing into the water heat exchanger 3 decreases.
Thus, it is possible to keep impairment of comfort during
defrosting operation little because the amount of heat taken away
from the indoor side through the water heat exchanger 3 is
relatively small. In other words, it is possible to suppress a
decrease in room temperature during defrosting operation, and to
reduce the power input to the compressor upon returning to heating
operation. As a result, it is possible to reduce the power
consumption.
Regarding the heat pump device 40, the configuration shown in FIG.
1 may be modified as follows. In such a case as well, it is
possible to obtain the same advantageous effects as those obtained
in the apparatus in FIG. 1.
(Modifications)
An opening/closing valve 9 may be provided between the water heat
exchanger 3 and the expansion valve 4a as shown in FIG. 9, and an
expansion valve 4c may be provided at a position that is on the
inlet side of the water heat exchanger 3 during defrosting
operation, as shown in (a) and (b) of FIG. 10. With such a
configuration, during defrosting operation, by closing the
opening/closing valve 9 or fully closing the expansion valve 4c, it
is possible to remove flow of the refrigerant flowing into the
water heat exchanger 3. In this case, the amount of heat taken away
from the load side (indoor side) decreases, and thus it is possible
to further improve the comfort in the room during defrosting
operation. In (a) of FIG. 10, 7b denotes a refrigerant container
that stores the refrigerant. In addition to the refrigerant
container 7b as shown in (a) of FIG. 10, the refrigerant container
7a which serves as a refrigerant buffer container may be
provided.
Embodiment 1 has been described with the four-way valve 2 as an
example of the second switching device, but the second switching
device is not limited to the four-way valve 2. For example, a
plurality of two-way passage switching valves or three-way passage
switching valves may be used as the second switching device, and
the second switching device may be configured such that flow of the
refrigerant is switched in the same manner.
In addition, Embodiment 1 has been described with the three-way
valve 6 as an example of the first switching device, but the first
switching device is not limited to the three-way valve 6. For
example, a plurality of two-way passage switching valves may be
used as the first switching device, or one flow path of a four-way
valve may be closed, whereby the first switching device may be
configured that the flow of the refrigerant is switched in the same
manner.
Embodiment 2
Embodiment 2 is intended to reduce the amount of work of a
compressor during defrosting operation.
FIG. 11 is a diagram showing a refrigerant circuit of an
air-conditioning system including a heat pump device of Embodiment
2 of the present invention. In FIG. 11, the same portions as those
in FIG. 1 are designated by the same reference signs. The same
applies to the embodiments to be described later. In addition, the
modifications applied to the same component portions as those in
Embodiment 1 are similarly applied to Embodiment 2. The same also
applies to the embodiments to be described later.
In addition to Embodiment 1 shown in FIG. 1, the heat pump device
of Embodiment 2 shown in FIG. 11 includes a refrigerant pump 1b
provided in parallel with the expansion valve 4a, and
opening/closing valves 12a and 12b for blocking a part of the flow
path of the refrigerant circuit 10, specifically, a flow path of
the four-way valve 2.fwdarw.the refrigerant container 7a.fwdarw.the
compressor 1.fwdarw.the water heat exchanger 3, during defrosting
operation, to separate the flow path from another flow path. In
addition, in the heat pump device 40 of Embodiment 2, the three-way
valve 6 in Embodiment 1 shown in FIG. 1 is omitted. The refrigerant
pump 1b is operated during defrosting operation and is stopped
during normal operation. In the heat pump device 40 of Embodiment
2, during defrosting operation, the compressor 1 is stopped, and
the refrigerant pump 1b is operated to circulate the refrigerant
through a later-described defrosting circuit A to perform
defrosting of the air-source heat exchanger 5a.
(Refrigerant Operation During Normal Operation (Heating
Operation))
The operation of the air-conditioning apparatus in normal
operation, particularly, in heating operation, according to
Embodiment 2 will be described. During heating operation, the
four-way valve 2 is switched to a side indicated by a dotted line
in FIG. 11.
FIG. 12 is a diagram showing flow of the refrigerant during heating
operation in Embodiment 2. Referring to FIG. 12, an alternate long
and short dashed line indicates a pipe portion through which the
refrigerant does not flow. In addition, the refrigerant pump 1b is
stopped, and the opening/closing valves 12a and 12b are opened.
The low-temperature and low-pressure refrigerant is compressed by
the compressor 1 into a high-temperature and high-pressure
refrigerant and discharged from it. The high-temperature and
high-pressure refrigerant discharged from the compressor 1 passes
through the four-way valve 2 switched for heating, flows into the
water heat exchanger 3, and rejects heat to the water in the water
circuit 51. The low-temperature and high-pressure refrigerant
obtained due to the heat rejection to the water divides into two
streams, which individually flow into the expansion valves 4a and
4b.
The refrigerant having flowed into the expansion valve 4a is
reduced in pressure, flows into the air-source heat exchanger 5a,
evaporates upon taking away heat from the outdoor air into a
low-pressure refrigerant, and flows out of the air-source heat
exchanger 5a. On the other hand, the refrigerant having flowed into
the expansion valve 4b is reduced in pressure, flows into the
earth-source heat exchanger 5b, and exchanges heat with the
earth-source side medium to take away heat from it. Upon this heat
exchange operation, geothermal heat is collected. Then, the
refrigerant having evaporated upon the collection of the geothermal
heat joins, at the junction and branch point P, the refrigerant
having flowed out of the air-source heat exchanger 5a of the main
circuit 10a, passes through the four-way valve 2 and the
refrigerant container 7a, and is drawn into the compressor 1 by
suction again.
(Refrigerant Operation During Defrosting Operation)
Next, the operation of the air-conditioning apparatus in defrosting
operation in Embodiment 2 will be described.
FIG. 13 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 2. Referring to FIG. 13, an
alternate long and short dashed line indicates a pipe portion
through which the refrigerant does not flow. FIG. 14 shows a p-h
diagram (a diagram showing the relationship between the pressure
and the specific enthalpy of the refrigerant) and is a diagram
showing the relationship between the operation state and the
temperature of the heat source side heat medium (the atmospheric
temperature and the underground temperature) during defrosting
operation in FIG. 13. Note that the geothermal temperature is
higher than the air temperature. In addition, referring to FIG. 14,
[i] (i=1, 2, . . . ) indicates a refrigerant state at each pipe
position shown by [i] (i=1, 2, . . . ) in FIG. 13.
In Embodiment 2, during defrosting operation, while the compressor
1 is stopped, the refrigerant pump 1b is operated, the
opening/closing valves 12a and 12b are closed, and the expansion
valve 4a is also closed. By so doing, a defrosting circuit A is
formed in which the refrigerant in the air-source heat exchanger 5a
circulates in order of the refrigerant pump 1b.fwdarw.the expansion
valve 4b.fwdarw.the earth-source heat exchanger 5b.fwdarw.the
air-source heat exchanger 5a, the air-source heat exchanger 5a
serves as a condenser, and the earth-source heat exchanger 5b
serves as an evaporator.
In such a defrosting circuit A, the refrigerant in state [1] flows
into the air-source heat exchanger 5a, condenses into a
low-temperature refrigerant (state [2]) upon rejecting heat to
frost adhering on the air-source heat exchanger 5a or the
atmosphere, and flows out of the air-source heat exchanger 5a. The
refrigerant having flowed out of the air-source heat exchanger 5a
is increased in pressure by the refrigerant pump 1b into a
refrigerant in state [3], and is subsequently reduced in pressure
by the expansion valve 4b into a refrigerant in state [4]. Then,
the refrigerant in state [4] flows into the earth-source heat
exchanger 5b and exchanges heat with the earth-source side medium
to take away heat from it. Upon this heat exchange operation,
geothermal heat is collected. Then, the refrigerant having
evaporated upon the collection of the geothermal heat flows into
the air-source heat exchanger 5a and rejects heat to the frost
adhering on the air-source heat exchanger 5a or the atmosphere as
described above. Thus, the frost adhering on the air-source heat
exchanger 5a is melted.
When the refrigerant circulates through the defrosting circuit A as
described above, it is possible to use an amount of heat collected
from the earth-source heat exchanger 5b as an amount of heat for
defrosting of the air-source heat exchanger 5a. In the case of this
cycle, since the condensing temperature of the air-source heat
exchanger is lower than the evaporating temperature of the
earth-source heat exchanger, in a state where the geothermal
temperature is higher than the air temperature by at least 0
degrees C., the condensing temperature of the air-source heat
exchanger is equal to or higher than 0 degrees C., and it is
possible to melt the frost.
Next, control action in defrosting operation in Embodiment 2 will
be described. Note that particularly, actuator action different
from that in Embodiment 1 will be described.
When the controller 30 determines that defrosting is required
during heating operation, the controller 30 stops the compressor 1
and closes the opening/closing valves 12a and 12b. Then, the
controller 30 operates the refrigerant pump 1b and circulates the
refrigerant through the defrosting circuit A. By so doing,
defrosting of the air-source heat exchanger 5a is performed with
the geothermal heat collected by the earth-source heat exchanger 5b
as described above. Then, when the controller 30 determines that
the defrosting operation is to end, the controller 30 stops the
refrigerant pump 1b, opens the opening/closing valves 12a and 12b,
operates the compressor 1, and performs heating operation
again.
As described above, according to Embodiment 2, during heating
operation, both the air-source heat exchanger 5a, which exchanges
heat with the atmosphere as a heat source, and the earth-source
heat exchanger 5b, which uses geothermal heat as a heat source,
serve as evaporators to collect heat from both the atmosphere and
another heat source. During defrosting operation, the compressor 1
is stopped, and it is possible to perform defrosting with the
refrigerant pump 1b as a power source. Thus, it is possible to
reduce the amount of work of the compressor during defrosting
operation. Therefore, it is possible to reduce the power
consumption during defrosting operation. In addition, the flow rate
of the refrigerant flowing into the water heat exchanger 3 is
reduced by stopping the compressor 1, and thus it is possible to
restrain the comfort from being impaired during defrosting
operation.
In Embodiment 2, the three-way valve 6 is omitted from the
configuration in Embodiment 1 shown in FIG. 1, but the three-way
valve 6 may be provided as shown in FIG. 15, similarly to
Embodiment 1. In the case of the configuration in which the
three-way valve 6 is provided, it is possible to appropriately
select either a method of performing defrosting with the defrosting
circuit A and a method of performing defrosting in a reverse mode
and perform defrosting. As a condition for appropriate selection
and defrosting, for example, the reverse mode is used in which it
is possible to collect heat from a room whose temperature is higher
than that of the outdoor air or underground is used in the case
where it is desired to complete defrosting quickly, and defrosting
with natural circulation or a refrigerant pump is performed in the
case where it is desired to reduce the power consumption as much as
possible.
In addition, in Embodiment 2, the refrigerant pump 1b is provided
in parallel with the expansion valve 4a in consideration of
pressure loss during normal operation, but the refrigerant pump 1b
only needs to be provided such that the refrigerant is allowed to
circulate between the air-source heat exchanger 5a and the
earth-source heat exchanger 5b.
In the case where the air-source heat exchanger 5a is disposed at a
position higher than the earth-source heat exchanger 5b, the
refrigerant undergoes natural circulation through the defrosting
circuit A due to a temperature difference being generated between
the air-source heat exchanger 5a and the earth-source heat
exchanger 5b. Thus, in this case, the refrigerant pump 1b is
unnecessary, and it is possible to further reduce the power
consumption during defrosting operation.
Embodiment 3
In Embodiment 1, during defrosting operation, heating operation is
stopped and the main circuit 10a is used for cooling operation.
However, in Embodiment 3, during defrosting operation, defrosting
is allowed to be also performed while heating operation is
continued.
FIG. 16 is a diagram showing a refrigerant circuit of an
air-conditioning system including a heat pump device of Embodiment
3 of the present invention.
The heat pump device 40 of Embodiment 3 is different from that of
Embodiment 1 in the position of the three-way valve 6.
Specifically, in Embodiment 3, in the main circuit 10a, the
three-way valve 6 is provided on a branch pipe 11b branching from a
pipe defined between the compressor 1 and the four-way valve 2, and
the end of the air-source heat exchanger 5a on its side opposite to
the expansion valve 4a is switched by the three-way valve 6 so as
to be connected to the earth-source heat exchanger 5b (the end of
the earth-source heat exchanger 5b on its side opposite to the
expansion valve 4b) or the discharge side of the compressor 1.
(Refrigerant Operation During Normal Operation (Heating
Operation))
The operation of the air-conditioning apparatus in normal
operation, particularly, in heating operation, according to
Embodiment 3 will be described. During heating operation, the
four-way valve 2 is switched to a side indicated by a solid line in
FIG. 16, and the three-way valve 6 is switched to a side indicated
by a dotted line in FIG. 16.
FIG. 17 is a diagram showing flow of the refrigerant during heating
operation in Embodiment 3. Referring to FIG. 1, an alternate long
and short dashed line indicates a pipe portion through which the
refrigerant does not flow.
The low-temperature and low-pressure refrigerant is compressed by
the compressor 1 into a high-temperature and high-pressure
refrigerant and discharged from it. The high-temperature and
high-pressure refrigerant discharged from the compressor 1 passes
through the four-way valve 2 switched for heating, flows into the
water heat exchanger 3, and rejects heat to the water in the water
circuit 51. The low-temperature and high-pressure refrigerant
obtained due to the heat rejection to the water divides into two
streams, which individually flow into the expansion valves 4a and
4b.
The refrigerant having flowed into the expansion valve 4a is
reduced in pressure, flows into the air-source heat exchanger 5a,
evaporates upon taking away heat from the outdoor air into a
low-pressure refrigerant, flows out of the air-source heat
exchanger 5a, and passes through the three-way valve 6. On the
other hand, the refrigerant having flowed into the expansion valve
4b is reduced in pressure, flows into the earth-source heat
exchanger 5b, and exchanges heat with the earth-source side medium
to take away heat from it. Upon this heat exchange operation,
geothermal heat is collected. Then, the refrigerant having
evaporated upon the collection of the geothermal heat joins, at the
junction and branch point P, the refrigerant having flowed out of
the air-source heat exchanger 5a of the main circuit 10a and having
passed through the three-way valve 6, passes through the four-way
valve 2 and the refrigerant container 7a, and is drawn into the
compressor 1 by suction again.
(Refrigerant Operation During Defrosting Operation)
Next, the operation of the air-conditioning apparatus in defrosting
operation in Embodiment 3 will be described. During defrosting
operation, each of the four-way valve 2 and the three-way valve 6
is switched to the side indicated by the solid line in FIG. 16.
FIG. 18 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 3. FIG. 19 shows a p-h diagram
(a diagram showing the relationship between the pressure and the
specific enthalpy of the refrigerant) and is a diagram showing the
relationship between the operation state and the temperature of the
heat source side heat medium (the atmospheric temperature and the
underground temperature) during defrosting operation in FIG. 18.
Note that the geothermal temperature is higher than the air
temperature. In addition, referring to FIG. 19, [i] (i=1, 2, . . .
) indicates a refrigerant state at each pipe position shown by [i]
(i=1, 2, . . . ) in FIG. 18.
The low-temperature and low-pressure refrigerant (state [1]) is
compressed by the compressor 1 into a high-temperature and
high-pressure refrigerant (state [2]) and discharged from it. The
high-temperature and high-pressure refrigerant discharged from the
compressor 1 is divided into two streams, and one of the two
streams passes through the four-way valve 2 switched for defrosting
(in the same manner as in heating) and flows into the water heat
exchanger 3. Then, the refrigerant having flowed into the water
heat exchanger 3 rejects heat to the water in the water circuit 51
to become a low-temperature and high-pressure refrigerant (state
[3]) and flows out of the water heat exchanger 3. The other stream
flows into the air-source heat exchanger 5a. Since a part of the
high-temperature and high-pressure refrigerant discharged from the
compressor 1 flows into the air-source heat exchanger 5a as
described above, it is possible to melt frost adhering on the
air-source heat exchanger 5a. Then, the refrigerant having flowed
into the air-source heat exchanger 5a rejects heat to the frost
adhering on the air-source heat exchanger 5a and the atmosphere to
become a low-temperature and high-pressure refrigerant (state
[3']), and then passes through the expansion valve 4a. It should be
noted that the expansion valve 4a is fully opened or is in a state
close to full open, and the refrigerant pass therethrough without
being reduced in pressure.
The refrigerant having passed through the expansion valve 4a joins
the refrigerant having flowed out of the water heat exchanger 3,
flows into the expansion valve 4b of the sub-circuit 10b, and is
reduced in pressure into a refrigerant in state [4]. The
refrigerant in state [4] flows into the earth-source heat exchanger
5b and exchanges heat with the earth-source side medium to take
away heat from it. Upon this heat exchange operation, geothermal
heat is collected. Then, the refrigerant having evaporated upon the
collection of the geothermal heat flows into the four-way valve 2,
passes through the refrigerant container 7a, and is drawn into the
compressor 1 by suction again.
In this defrosting operation, heating operation is continuously
performed in the main circuit 10a even during defrosting operation.
Thus, it is possible to perform defrosting of the air-source heat
exchanger 5a while the comfort in a room is maintained. In
addition, in the earth-source side circuit 20, geothermal heat is
collected by the underground heat exchanger 21 and transmitted to
the main circuit 10a through the sub-circuit 10b. Thus, during
defrosting, in addition to the amount of work of the compressor 1,
it is possible to use the amount of heat collected from the
earth-source heat exchanger 5b, as an amount of heat for defrosting
and also as an amount of heat for heating.
Next, control action in defrosting operation in Embodiment 3 will
be described. Note that particularly, actuator action different
from that in Embodiment 1 will be described.
When the controller 30 determines that defrosting is required
during heating operation, the controller 30 does not switch the
flow path of the four-way valve 2 and keeps the flow path for
heating, and switches the flow path of the three-way valve 6 to the
discharge side of the compressor 1 such that the refrigerant
discharged from the compressor 1 flows into the air-source heat
exchanger 5a. By so doing, the refrigerant discharged from the
compressor 1 flows into the water heat exchanger 3 and the
air-source heat exchanger 5a, each of the water heat exchanger 3
and the air-source heat exchanger 5a serves as a condenser, and the
earth-source heat exchanger 5b serves as an evaporator. Then, when
the controller 30 determines that the defrosting operation is to
end, the controller 30 switches the flow path of the three-way
valve 6 to the side of the earth-source heat exchanger 5b and
performs heating operation again.
As described above, according to Embodiment 3, during heating
operation, both the air-source heat exchanger 5a, which exchanges
heat with the atmosphere as a heat source, and the earth-source
heat exchanger 5b, which uses geothermal heat as a heat source,
serve as evaporators to collect heat from both the atmosphere and
another heat source. During defrosting operation, the earth-source
heat exchanger 5b serves as an evaporator to collect geothermal
heat, thus the amount of heat that can be used during defrosting
operation increases, and it is possible to shorten the defrosting
period of time.
In addition, since a part of the refrigerant discharged from the
compressor 1 flows into the water heat exchanger 3, heating
operation is enabled even during defrosting operation, and it is
possible to restrain the comfort from being impaired during
defrosting operation. Thus, it is possible to suppress a decrease
in room temperature during defrosting operation, and it is possible
to reduce the power input to the compressor upon returning to
heating operation. As a result, it is possible to reduce the power
consumption.
Moreover, according to Embodiment 3, it is possible to use the
amount of work of the compressor 1 and the amount of heat collected
from the earth-source heat exchanger 5b, as an amount of heat for
defrosting of the air-source heat exchanger 5a and also as an
amount of heat for heating.
Embodiment 4
FIG. 20 is a diagram showing a refrigerant circuit of an
air-conditioning system including a heat pump device of Embodiment
4 of the present invention. The heat pump device 40 of Embodiment 4
has a configuration in which, in the heat pump device 40 of
Embodiment 3 shown in FIG. 16, the branch pipe 11b is omitted but
an auxiliary compressor 1c is newly added to the main circuit 10a.
In addition, in the heat pump device 40 of Embodiment 4, the
air-source heat exchanger 5a communicates with the discharge side
of the auxiliary compressor 1c or the side of the earth-source heat
exchanger 5b (the side of the refrigerant flow path 41 of the
earth-source heat exchanger 5b opposite to the expansion valve 4b)
by switching of the three-way valve 6. Moreover, an expansion valve
4c is provided between the water heat exchanger 3 and the expansion
valves 4a and 4b to allow the flow rate of the refrigerant flowing
into the water heat exchanger 3 to be controlled.
(Refrigerant Operation During Normal Operation (Heating
Operation))
The operation of the air-conditioning apparatus in normal
operation, particularly, in heating operation, according to
Embodiment 4 will be described. During heating operation, the
four-way valve 2 is switched to a side indicated by a sold line in
FIG. 20, and the three-way valve 6 is switched to a side indicated
by a dotted line in FIG. 20.
FIG. 21 is a diagram showing flow of the refrigerant during heating
operation in Embodiment 4. Referring to FIG. 21, an alternate long
and short dashed line indicates a pipe portion through which the
refrigerant does not flow. In addition, operation of the auxiliary
compressor 1c is stopped, and the expansion valve 4c is fully
opened.
The low-temperature and low-pressure refrigerant is compressed by
the compressor 1 into a high-temperature and high-pressure
refrigerant and discharged from it. The high-temperature and
high-pressure refrigerant discharged from the compressor 1 passes
through the four-way valve 2 switched for heating, flows into the
water heat exchanger 3, and rejects heat to the water in the water
circuit 51. The low-temperature and high-pressure refrigerant
obtained due to the heat rejection to the water divides into two
streams, which individually flow into the expansion valves 4a and
4b.
The refrigerant having flowed into the expansion valve 4a is
reduced in pressure, flows into the air-source heat exchanger 5a,
evaporates upon taking away heat from the outdoor air into a
low-pressure refrigerant, flows out of the air-source heat
exchanger 5a, and passes through the three-way valve 6. On the
other hand, the refrigerant having flowed into the expansion valve
4b is reduced in pressure, flows into the earth-source heat
exchanger 5b, and exchanges heat with the earth-source side medium
to take away heat from it. Upon this heat exchange operation,
geothermal heat is collected. Then, the refrigerant having
evaporated upon the collection of the geothermal heat joins, at the
junction and branch point P, the refrigerant having flowed out of
the air-source heat exchanger 5a of the main circuit 10a and having
passed through the three-way valve 6, passes through the four-way
valve 2 and the refrigerant container 7a, and is drawn into the
compressor 1 by suction again.
(Refrigerant Operation During Defrosting Operation)
Next, the operation of the air-conditioning apparatus in defrosting
operation in Embodiment 4 will be described. During defrosting
operation, each of the four-way valve 2 and the three-way valve 6
is switched to a side indicated by a solid line in FIG. 20.
FIG. 22 is a diagram showing flow of the refrigerant during
defrosting operation in Embodiment 4. FIG. 23 shows a p-h diagram
(a diagram showing the relationship between the pressure and the
specific enthalpy of the refrigerant) and is a diagram showing the
relationship between the operation state and the temperature of the
heat source side heat medium (the atmospheric temperature and the
underground temperature) during defrosting operation in FIG. 22.
Note that the geothermal temperature is higher than the air
temperature. In addition, referring to FIG. 23, [i] (i=1, 2, . . .
) indicates a refrigerant state at each pipe position shown by [i]
(i=1, 2, . . . ) in FIG. 22.
The low-temperature and low-pressure refrigerant (state [1]) is
compressed by the compressor 1 into a high-temperature and
high-pressure refrigerant (state [2]) and discharged from it. The
high-temperature and high-pressure refrigerant discharged from the
compressor 1 passes through the four-way valve 2 and flows into the
water heat exchanger 3. The refrigerant having flowed into the
water heat exchanger 3 rejects heat to the water in the water
circuit 51 to become a low-temperature and high-pressure
refrigerant (state [3]), flows out of the water heat exchanger 3,
and then is reduced in pressure by the expansion valve 4c. The
refrigerant having been reduced in pressure by the expansion valve
4c is further reduced in pressure by the expansion valve 4b of the
sub-circuit 10b, flows into the earth-source heat exchanger 5b, and
exchanges heat with the earth-source side medium to take away heat
from it. Upon this heat exchange operation, geothermal heat is
collected.
Then, the refrigerant having evaporated upon the collection of the
geothermal heat divides into two streams at the junction and branch
point P before the four-way valve 2, and one of the two streams
flows into the four-way valve 2, passes through the refrigerant
container 7a, and is drawn into the compressor 1 by suction. The
other stream passes through the three-way valve 6, flows into the
auxiliary compressor 1c, increases in temperature and pressure here
into a high-temperature and high-pressure refrigerant (state [2']),
and flows into the air-source heat exchanger 5a. Since the
air-source heat exchanger 5a serves as a condenser, the refrigerant
having flowed into the air-source heat exchanger 5a condenses into
a low-temperature and high-pressure refrigerant (state [3']) upon
rejecting heat to frost adhering on the air-source heat exchanger
5a or the atmosphere. The low-temperature and high-pressure
refrigerant is reduced in pressure by the expansion valve 4a, joins
the refrigerant having been reduced in pressure by the expansion
valve 4c in the main circuit 10a, flows into the expansion valve
4b, and is further reduced in pressure into a refrigerant in state
[4]. The refrigerant in state [4] flows into the earth-source heat
exchanger 5b and exchanges heat with the earth-source side medium
to take away heat from it to become a high-temperature and
low-pressure refrigerant (state [1]) again.
In this defrosting operation, the amount of work of the compressor
1 is used by the water heat exchanger 3 as an amount of heat for
heating on the load side, and the amount of work of the auxiliary
compressor 1c is used as an amount of heat for defrosting of the
air-source heat exchanger 5a.
Next, control action in defrosting operation in Embodiment 4 will
be described. Note that particularly, actuator action different
from that in Embodiment 3 will be described.
When the controller 30 determines that defrosting is required
during heating operation, the controller 30 does not switch the
flow path of the four-way valve 2 and keeps the flow path for
heating, and switches the flow path of the three-way valve 6 such
that the refrigerant having flowed out of the earth-source heat
exchanger 5b flows into the auxiliary compressor 1c. By so doing, a
part of the refrigerant, in the earth-source heat exchanger 5b,
having collected the geothermal heat through the earth-source side
medium in the earth-source side circuit 20 is increased in
temperature and pressure by the auxiliary compressor 1c and then
flows into the air-source heat exchanger 5a, and defrosting of the
air-source heat exchanger 5a is performed. Then, when the
controller 30 determines that the defrosting operation is to end,
the controller 30 switches the flow path of the three-way valve 6
such that the side of the air-source heat exchanger 5a opposite to
the expansion valve 4a is connected directly to the earth-source
heat exchanger 5b without being connected via the auxiliary
compressor 1c, stops the auxiliary compressor 1c, and performs
heating operation again.
In addition, during defrosting operation, the controller 30
appropriately controls the expansion valve 4c to increase the
amount of refrigerant flowing into the air-source heat exchanger 5a
and reduce the amount of refrigerant flowing into the water heat
exchanger 3. By so doing, it is possible to quickly end the
defrosting of the air-source heat exchanger 5a. When the amount of
refrigerant flowing into the water heat exchanger 3 is reduced, the
capacity of heating the room decreases, and thus the expansion
valve 4c may be controlled in view of balance between ensuring
comfort in the room and promotion of defrosting.
As described above, in Embodiment 4, during heating operation, both
the air-source heat exchanger 5a, which exchanges heat with the
atmosphere as a heat source, and the earth-source heat exchanger
5b, which uses geothermal heat as a heat source, serve as
evaporators to collect heat from both the atmosphere and another
heat source. Then, during defrosting operation, the refrigerant
having been increased in temperature and pressure by the auxiliary
compressor 1c flows into the air-source heat exchanger 5a, and the
flow path of the three-way valve 6 is switched such that geothermal
heat is collected by the earth-source heat exchanger 5b and a part
of the refrigerant flowing toward the water heat exchanger 3 flows
into the air-source heat exchanger 5a. By so doing, it is possible
to use the heat collected from the underground through the
earth-source heat exchanger 5b, as an amount of heat for both
heating and defrosting. Since the amount of heat that can be used
for defrosting increases by the amount of heat collected from the
underground, it is possible to reduce the defrosting period of
time.
In addition, even during defrosting operation, the water heat
exchanger 3 serves as a condenser to enable heating operation, and
thus it is possible to restrain the comfort from being impaired
during defrosting operation.
Moreover, in Embodiment 4, by adjusting the power input to each of
the compressor 1 and the auxiliary compressor 1c, it is possible to
make the condensing temperature of the water heat exchanger and the
condensing temperature of the air-source heat exchanger different
from each other as shown in FIG. 23. Thus, while the condensing
temperature for heating (the condensing temperature of the water
heat exchanger) is maintained, defrosting operation is enabled in
which the condensing temperature of the air-source heat exchanger
is not increased more than necessary, and it is possible to reduce
the power consumption during defrosting. In other words, the
condensing temperature of the air-source heat exchanger suffices to
be a temperature that melts frost, and thus may be lower than the
condensing temperature for heating, and it is possible to reduce
the power consumption since it is possible to lower the condensing
temperature.
It should be noted that in each embodiment described above, the
example has been described in which geothermal heat is used as a
heat source other than the atmosphere, but the heat source other
than the atmosphere is not limited to geothermal heat, and
groundwater, seawater, or solar hot water may be used as a heat
source.
In addition, in general, it is possible to use heat generated by an
electric heater or a boiler on the load side during heating
operation as it is, but an amount of heat is insufficient when the
geothermal heat or the heat of groundwater, seawater, or solar hot
water that is lower than a temperature set for the load side is
used as a heat source for making the load side at the set
temperature. However, with the heat pump device 40 of each
embodiment described above, it is possible to use the geothermal
heat or the heat of groundwater, seawater, or solar hot water as a
part of a heat source for defrosting, and it can be said that it is
effective for reducing the power consumption during defrosting
operation.
It should be noted that the configuration with the four-way valve 2
has been shown in each embodiment described above, but the four-way
valve 2 is not necessarily essential and may be omitted in
Embodiments 2 to 4.
In addition, in the case where a second switching device is
provided in Embodiments 2 to 4, the second switching device is not
limited to the four-way valve 2 similarly to Embodiment 1, a
plurality of two-way passage switching valves or three-way passage
switching valves may be used and configured such that flow of the
refrigerant is switched in the same manner as the four-way valve
2.
Furthermore, Embodiments 2 to 4 have been described with the
three-way valve 6 as an example of the first switching device, but
the first switching device is not limited to the three-way valve 6
similarly to Embodiment 1. For example, a plurality of two-way
passage switching valves may be used as the first switching device,
or one flow path of a four-way valve may be closed, whereby it is
configured that the flow of the refrigerant is switched in the same
manner.
In addition, in each embodiment described above, the example of the
air-conditioning system has been described as an apparatus to which
the heat pump device 40 is applied, but the apparatus is not
limited thereto and may be a hot-water supply system. In short, the
apparatus may be a system that performs heat applying operation in
which the refrigerant circulates such that the load side heat
exchanger (the water heat exchanger 3) serves as a radiator and the
air-source heat exchanger 5a serves as an evaporator.
INDUSTRIAL APPLICABILITY
A heat pump device including multiple heat sources is useful as an
application example of the present invention.
* * * * *